Air compressor



March 27; 1945.

"Fig.2 66 45 F 3:: g 5 \w 44 10 ll ,3

G. K. NEWELL' AIR COMPRESSOR Filed'Nov. 2, 1943 2 Sheets-Shet 2 I 7 INYENTOR GEORGE K. NE WEL L BY a? ATTORNEY Patented Mar. 27, 1945 AIR COMPRESSOR George K. NewelLflnear Pitcairn, Pa., assignor. to

The Westinghouse Air Brake, Company, Wilmerding; Pa.., a corporation'of Pennsylvania Application November 2, 1.9.43, Serial No. 508,682

Claims.

sity for working to very close manufacturing tolerances in order to prevent. leakage past the vanes or other fluid compressing elements. In

rotary compressors heretofore proposed, the operating parts have usually' :beensubject-to excessive-friction causing rapid. wearof the'fluid"compressing elements, whichv condition has generally been made more severe due to the difilculty'of providing adequate lubrication.

It is an object of my invention to provide an improved rotary fluid compressorhaving a relatively-simple and sturdy construction, and which is designed for manufacture at a low cost by application of modern mass'production techmques;

It is another object-of"the-inventionto provide an improved rotary compressor includinga' fluid compressing member having an eccentric rolling motion and operativexto compress fluidiby'a novel a pplication o-f centrifugal forcer developed through the medium of a flexible driving means.

are spaced inwardly'from the outer or'peripheral wall: Ina thereof. 0n reference to Fig. 3 of the drawings; the outer wall Illa of theannular compression chamber l0 will be" seen to be arcuate in section;

Slidably mounted within the; channel ill be.- tween the head plate 8 and theenlarged portion 7- of the housing is anv annular fluid compressing member orrotary, piston member I5, the maxi mum. diameter of which is smaller than that of the channel, to permit eccentric operation of the, rotary. piston to uncover a number of the inlet ports H at one: side, at any given moment, while the opposite side of the-piston member engages the convex wall Illa, asis best shown in Fig. 2 of the drawings. The peripheral wallv IBI of the rotary piston 15 is madeconcave in form to correspond with the wall 10a: of'the channel llLas shown in Fig. 3. Aplurality' of annular'packing rings IT, preferably formedof-a carbonaceous or' other self-lubricating material, may be mounted in suitable annular grooves formed in "the rotary piston 15. Thepacking rings I I are Other objects and advantages'ofthe invention .will appear in the following more detailed description thereof, taken in connection with. the accompanying drawings, in which Fig. 1 isavertical sectional view, of arotary fluid compressor constructed in accordance with the invention;

Fig. 2 is a plan View; partly in section, of the compressor shown in'Fig. 1;; and

Fig. 3 isa fragmentary. sectionalviewv taken substantially along the lined-f Fig.2..

Referring to-Fig. 1 of the-drawings; thecompressor. may comprise a generally cylindrical housing 5 having. a bearing. portion li-formedat one end thereof and an enlargedannular portion spaced apertures l2 formed in the adjacentLwall of. the housing 5, as shown..in.Fig..3.. Tommi.- mize. passage of. dust through the. inlet ports formed in the headplate..8,,a.screen I3. is preferably secured thereto. by means of. a. snap'ring I4. It willbe noted. that. the. inlet ports II are disposed at the sides of the channel Ill and arranged on both lateral sidesof therotary piston for engagement withthe walls of the channel I0 provided by the casing portion land by the head plate 8, respectively.

The rotary piston l5 has an annular recess 13 within which is secured the peripheral flange of aflexible disk-shaped web member 20', which may be made of a suitable yieldable material such as a rubberized fabric leather, or compo-, sition, and whichis adapted to be firmly held in place within the rotary piston by means of a pair of'snap rings 22 and 23. Mounted in the bearing portion 6 of the housing 5 is a ball bearing assembly 25, within which is journaled a rotary shaft 26. carrying on its outer. end a sheave 2'l.- The endof the shaft 26 within the housing 5 carries a circular flange 30, the peripheral portion of which is. secured by'rivets' 32' to a flexible web member 3.| that is formed of the same material as that of which. the web member 20' is composed. For coupling the two web members 3| and 20 together, there is provided a connecting rod 35, which isnormally disposed'along the axis of the web members and has a, head 36 secured by means of rivets 31 to the central portion of the web member 20, and a head portion 38 similarly secured by means of rivets39 to the central portion of the. web member 3|.

As is best shown in Fig. 2, the circular channel. I0 is divided into. four compartments, or chambers, by means of four plungers 42, which are operatively mounted in the portion 1 of the casing structure and are disposed radially at equally spaced points about the annular rotary piston l5. Each of the plungers 42 is slidably mounted within a bore 53 formed in the casing portion 1 and extends into a similar bore 44 formed in a cap member 45 having screw-threaded connection with the casing. A coil spring 45 is interposed between the inner wall of each cap member 45 and the adjacent plunger 42 for urging the plunger inwardly and into sliding engagement with the annular piston 15. It will be observed that the inner end of each plunger 42 adjacent the annular piston 15 is suitably rounded to insure proper sealing engagement with the concave surface I6 of the rotary piston, as is best shown in Fig. 1. Each. of the plungers 42 is of course adapted to engage the opposite lateral walls of the channel Ill provided by the casing portion 1 and by the end plate 8 previously described, so as to form substantially pressuretight partitions dividing the circular channel.

In Fig. 2 of the drawings the division of the circular channel it into four compartments, by the plungers 42 engaging the annular piston I5, is clearly represented. Air to be compressed can be drawn through the inlet ports I I into each of the compartments of the channel in thus constituted and then compressed therein, upon rotation of the annular piston member as hereinafter explained, the compressed air being discharged from each compartment into a manifold pipe 50 by way of one of a plurality of discharge valve assemblages that are disposed in pairs intermediate the plungers '42.

Each of the discharge valve assemblages 50 comprises a body member 53 bolted to the portion 1 of the compressor casing, and having formed therein a passage 54 communicating with a valve chamber 55 and with a T fitting 55 connected to the curved manifold pipe 5!! surrounding the compressor. A valve element 5! mounted within each valve chamber 55 is adapted to be urged into seating engagement with a seat rib 58 under the force of a coil spring 59 for controlling communication, by way of a port 6t, from the adjacent compartment of the annular channel to the valve chamber. It will be understood that two ports 50 are preferably provided for each of the four compartments of the channel In formed between the plungers 42 in order to insure v01- umetric efficiency in the compressing of air regardless of the direction of rotation of the annular piston member [5.

In operation, the sheave 21 is connected by means of a driving belt to a suitable driving means, not shown, and is rotated at a high speed to operate the annular piston member through the medium of the shaft 25. flexible web member 3!, rod 35, and flexible web member 20. The annular piston member l5 and web member are normally urged by the spring-pressed plungers 42 into substantially coaxial alignment with respect tothe web member 3| and shaft 26, so that during initial rotation of these elements, the piston mem ber at first slides concentrically within the annular channel Ill. The absence of any positive centering guide, however, soon results in lateral, offcenter movement of the more rapidly rotating piston member I 5 until it is thrown into rolling contact with the peripheral wall Hla of the channel, forcing outwardly each of the plungers 42 in turn as it travels through the channel Hi.

It will be understood that the mass of the annular piston member I5 is considerable, so that as it is constrained to roll around the peripheral wall of the recess ID at high speed, the centrifugal force holding the piston member in rolling contact with the peripheral surface Illa becomes relatively great. As the annular piston member is thus operated eccentrically, it uncovers the in let ports H in succession to draw into each corresponding compartment of the annular channel III the air to be compressed. The air thereby trapped in the compartments formed between the spaced plungers 42 is then subjected to compression under a force corresponding to the centrifugal force developed by the rapidly rolling annular piston member l5, the compressed air being forced outwardly past the series of discharge valve elements 51 to the manifold pipe 50 encircling the compressor.

Inasmuch as the annular piston member I5 is of smaller diameter than that of the circular channel H) in which air is compressed, it will be obvious that somewhat more than one revolution of the piston member will occur before the point of rolling contact between the annular piston member and the wall Illa travels through a complete cycle. Hence the number of revolutions of the contact point continually falls behind the number of revolutions of the annular piston member during operation of the compressor. This result is made possible by the operation of the flexible web members 20 and 3!, which are adapted to be flexed through an infinite number of different positions and thus do not impose any definite positional relationship between the point of rolling contact and the rotation of the annular piston member. It will thus be understood that the annular piston member I5 will normally be operated in constant rolling contact with the peripheral surface Illa of the air compression channel ID in such a manner as to reduce to a minimum the wear and excessive development of heat that might accompany a slipping or sliding condition of the cooperating elements.

A further advantage of my invention springs from the fact that the eccentric motion of the annular piston member 15 and of the packing rings I! carried thereby is not one of true con centric sliding, but is rather of a form of hypocycloidal motion, in which are combined a lateral oscillatory motion and a certain amount of circular sliding, so that the resultant average rubbing speed of the packing rings on the walls of the annular channel l0 will be considerably less than would be the case if the piston member were rotated concentrically within the housing.

From the foregoing description, it will be apparent that the relatively simple structural features of my improved compressor will enable production of each unit at a low cost, and operation of' each device with a moderate power consumption to deliver compressed air that is free from the lubricating oiloften discharged by conventional compressors.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A fluid compressor comprising a casing having a circular compression channel opening inwardly, a plurality of spaced yieldable partition elements extending into said channel, lateral inlet ports formed in said casing in communication with said channel, discharge valve means mounted in said casing outwardly of said channel, an annuin for operation in overlapping relation with said inlet ports successively, said compressing element having a peripheral surface engageable with said partition elements, and flexible driving means operative to rotate said element in eccentric rolling relation in said channel for progressively uncovering said inlet ports, then covering same while trapping and compressing fluid between said partition elements. I

2. A fluid compressor comprising a casing having a circular compression channel opening inwardly, a plurality of spaced yieldable partition elements extending into said channel, lateral inlet ports formed in said casing in communication with said channel, discharge valve means mounted in said casing outwardly of said channel, an annular compressing element of smaller diameter than that of said channel and slidably mount ed therein, said compressing element having a peripheral surface engageable with said partition elements for rendering same effective to prevent backflow of fluid through said inlet ports, and flexible driving means operative to rotate said element in eccentric rolling relation in said channel for progressively trapping and compressing fluid between said partition elements; said driving means including a flexible web element having its peripheral portion secured to said annular compressing element, a rotary drive shaft journaled in said casing, another flexible web element having its peripheral surface secured to said drive shaft, and a connecting element having its ends secured to the central portions of said web elements, respectively.

3. A fluid compressor comprising a casing, ro tary fluid compressing means operatively mounted in said casing, fluid inlet and-discharge means associated in said casin with said rotary fluid compressing means, movable partition means mounted in said casing for cooperation with said fluid compressing means and arranged between said inlet and discharge means during compression of fluid, a rotary driving shaft journaled in said casing, a flexible disk element secured concentrically to said rotary fluid compressing means, a flexible disk element carried by said drive shaft, and connecting means joining said flexible disk elements together, whereby said rotary fluid compressing means is constructed and arranged for eccentric rotation in rolling contact with an interior portion of said casing by operation of said drive shaft.

4. A fluid compressor comprising a casing having a circular compression channel opening inwardly with an annular bottom wall and flat, side walls, a plurality of concentrically spaced lateral inlet ports formed in said side walls, a plurality of discharge valve means mounted in said casing and including outlet ports communicating with said channel, an annular fluid compressing element of smaller diameter than that of said channel and having flat lateral surfaces slidably engaging said side walls, said compressing element also having a peripheral surface adapted for rolling engagement with said annular bottom wall of said channel for operation to uncover a number'- of the inlet ports at one side at any given moment while those at the opposite side are closed, a, plurality of equally spaced yieldable partition elements extending into said channel in sealing relation with the side walls thereof, said yieldable partition elements having end surfaces disposed in sliding engagement with said peripheral surface of the compressing element for at any given moment cutting off communication between the uncovered inlet ports and the outlet ports of said discharge valve means'through which fluid is being discharged under compression, and flexible driving means operative to rotate said compressing element in centrifugal rolling relation in said channel for progressively uncovering said inlet ports, then covering same while trapping and compressing fluid between said partition elements.

' 5. A fluid compressor comprising a casing having a circular compression channel opening inwardly with an annular bottom wall and flat side walls, a plurality of concentrically spaced lateral inlet ports formed in said side walls, a plurality of discharge valve means mounted in said casing and including outlet ports communicating with said channel, an annular fluid compressing element of smaller diameter than that of said channel and having flat lateral surfaces slidably engaging said side Walls, said compressing element also having a peripheral surface adapted for rolling engagement with said annular bottom wall of said channel for operation to uncover a number of the inlet ports at one side at any given moment while those at the opposite side are closed, a plurality of equally spaced yieldable partition elements extending into said channel in sealing relation with the side walls thereof, said yieldable partition elements having end surfaces disposed in sliding engagement with said peripheral surface of the compressing element for at any given moment cutting oif communication between the uncovered inlet ports and the outlet ports of said discharge valve means through which fluid is being discharged under compression, and flexible driving means operative to rotate said compressing element in centrifugal rolling relation in said channel for progressively trapping and compressing fluid between said partition elements, said driving means including a flexible web element having its peripheral portion secured to said annular compressing elements, a, rotary drive shaft journaled in said casing, another flexible web element having its peripheral surface secured to said drive shaft, and a rigid connecting element having its ends secured to the central portions of said web elements, respectively.

GEORGE K. NEWELL. 

